Study And Design Of A Volume Calibration System Of Underground Tank Based-on Laser Scanning

With the development of the national economy and transportation, growth in number of motor vehicles every year brings the flourish of gas station industry. However, the industry tax burden is declining, resulting in serious loss of state taxes.In order to block the loopholes in the tax administration, state tax thereon have cancelled a single regulatory approach of tax fuel dispenser installed in the link of traditional sales in the gas station to calculate amount of tax, while began to strengthen tax administration meanwhile in links of purchasing, inventory, sales, and have developed and applied monitoring system. This system need using the oil tank volume table to calculate the volume after measuring the height of inventory oil. The volume table is measured by Technical Supervision Bureau in accordance with the relevant national standards and regulations. As the gas station underground tanks is the horizontal cylindrical storage steel tanks, volume is measured in accordance with the requirements of the standard before the installation.Almost all of the tank will be tilted due to the tank foundation sinking during operation. Meanwhile, the horizontal radius of the tank will increase and vertical radius will decrease owing to the effect of the pressure generated by internal oil and the extrusion between groundwater buoyancy and Overburden pressure. Therefore, tanks need to re-verification after operating for a period of time. Verification of underground oil tank has been a difficulty in the area of volume measurementAccording to National Standards and Metrological Measuring Standards, measuring method of buried oil tank should be calibrated in manual method by Technical Supervision Bureau. However, this brings heavy measured task, poor working environment, more time-consuming and long measured period in which it will seriously affect the station's normal business. Therefore, man-calibrated method is often used to improve the measuring environment, there are still problems of heavy workload, more time-consuming and it is difficult to guarantee the uncertainty of measurement.This thesis proposes method of laser scanning in the tomography one by one based on the volume of geometric measurement, after draws on the measurement of other types of tanks.Measurement and control system consists of a PC, a motion controller, two stepping motor, detection-mechanism, optical encoders, laser range sensors and other components. After start measurement, PC machine divide automatically height to a number of tomography by the algorithm of Z-axis step, then laser ranging sensor is driven by the detection-mechanism to uniform rotation and be placed on tomography one by one The PC calculates automatically the proper angle as the sample point by location algorithm, and collects angle value from incremental optical encoder and the distance value from the laser range sensor when arrived to the sample point.For the obtained discrete measurement points in the scan line as sampled data, the method of data post-processing is that interpolate firstly scanning curve with cubic spline, then calculate integration of the interpolated curve. As 3 polynomial, the cubic spline curve can theoretically be derived its original function to further increase the integration accuracy and reduce the computational load.This method is of high degree of automation, measurement speed, simple instrumentation operation, no artificial error in data processing, which can reduce the closure of gas stations in the detection time.